Gout patients have recently increased and the onset age has become younger. Gout is a disease caused by tissue deposition of monosodium urate crystals, and often has the onset as a result of inflammation of the joint. Also, gout is frequently found in hyperuricemia patients, and it has long been known to have a heritable component.
Gout is often associated with hypertension, obesity, diabetes, coronary artery diseases, cerebrovascular diseases, kidney diseases and the like. Also, inflammation-related diseases include rheumatoid arthritis, infertility and the like, and early treatment and prevention of these diseases are needed.
The present inventors have demonstrated that loss-of-function mutations in two urate transporter genes, i.e., urate transporter 1 (URAT1/SLC22A12) and glucose transporter 9 (GLUT9/SLC2A9), cause renal hypouricemia using function-based genetic analysis (MIM220150 and MIM612076, respectively) (Non-Patent Literatures 1 and 2). These findings, together with their renal expression patterns, also show that URAT1 and GLUT9 mediate renal urate reabsorption in human.
However, other urate transporters have not been identified so far by such analysis, and urate transporters that increase the serum uric acid (SUA) level and have main pathogenic mutations causing gout or hyperuricemia remain unidentified.
The prior art relating to a urate transporter is disclosed in Patent Literature 1, and the prior arts relating to ABCG2 as a transporter are disclosed in Patent Literatures 2 to 4. However, the prior arts disclose the ABCG2 as a transporter of a drug, but not disclose its involvement in urate transport nor in urate transport-related disease factor and inflammation-related disease factor.